Sap Lfter acting like a Sap Ladder?

[johnallin]

The photos are helpful but it's not clear which line is meant to be the dryline bypass. It looks like the green line is your mainline coming into the manifold above the lifter, along with a bunch of laterals. And the light blue (vs. the purple blue) line is a dryline. If this is the case then it seems like the dryline bypass should run further upstream of the manifold and it should completely bypass the manifold and lifter. Instead, it should run up above the mainline on the vacuum pump side, including a loop above that mainline.

Also, CDL recommends five feet of elevation difference from the lower side of the bypass connection to the lower mainline for each 100 taps. I think this is to provide storage capacity in the line as the lifter is discharging. Your manifold will serve the same purpose. But if you added taps this season then it would explain why you have problems this year but not previously.

I'm also wondering if the connection from the manifold to the lifter is partly blocked causing the sap to back up to the bypass.
Ken

In the picture, the dryline is marked with red, lifter line in yellow. Dryline is off the "Y" fitting at the end of the green mainline. The other two coming off the mainline dump into the manifold.
Not sure if the second is needed, but that's the way it was designed. Number of taps has not changed significantly since last year...maybe 15-20 added. The manifold does not fill, it just pours into the lifter.

[GeneralStark]

I don't think there is anything wrong with your plumbing, especially given the fact that the system has worked for several years. You could probably just run the dry line into the manifold directly and do the same with the green mainline but that's not going to fix your issue. It would just simplify things. You have a leak somewhere upstream of the lifter, and probably a good sized one. You'll have to go over the all the 3/16 lines and everything on the green mainline. I would also suspect that union between the manifold and lifter and any other fitting upstream of the lifter. I have had cracked unions and it looks like you have a stainless nipple there which can be problematic.....

It looks as though you have valves on the 3/16 lines so that should help isolate potential leaks there. Valves on the other lines coming into the manifold would also help.

My lifter was set up similar with a manifold (booster) and dedicated dryline to the manifold. There were four 3/4 mainlines coming into the manifold for a total of about 200 taps. Each line was valved and this made finding leaks much easier. I often ran into the same issue you're having when there leaks on the 3/4 lines. Shutting off all the valves confirmed there was no issue at the lifter, which occasionally there was. The drain valve (i plugged it) was a frequent leaker....I don't shut off the vacuum and kept the lifter and manifold in a heated enclosure.

These lifters are really pretty basic as long as there is no air coming into the system which will bypass the float and plunger (as you are experiencing)...As you know, the lift occurs when the leak is introduced by the float and plunger. If the leak is somewhere upstream, the same thing is going to happen without the float and plunger doing it. It will still function correctly with a small leak upstream but there is a fine line.... your leak is too big.

One question... when you say "The dry line bypass is also pulling sap straight up", what are you referring to as the "dry line bypass"? The float/plunger plug or one of the lines coming into the manifold off the dry line?

[johnallin]

Thanks for the response.
The dryline bypass I refer to is the one with the red arrow. It is also pulling straight up from the end of the green main line, as is the return line from the lifter (marked with a yellow arrow).

You're right that I have SS ball valves at each 3/16 line and have closed them with no change in vacuum.

Essentially the Dry line and green mainline do run directly into the manifold. Dry comes in from the top of the high return line to the releaser (like a whip) and goes to the "Y" at the end of the green main line. There is a blue line at this "Y" that goes straight to the manifold. There is a "T" just before that with another line dropping from the green main line down to the manifold.

Going to try a CDL leak detector from Fred and see what I can find...but we're pulling lots of sap as it is and I just don't have time to start tearing everything apart.
I've already wasted two days monkeying around and I'm done with that. If it finds the leak I'm buying the detector and will repair whatever it is when I have time.

[GeneralStark]

Seems as though a walk out that green line is the thing to do. The air (from the leak) is following the path of least resistance back to the releaser and is carrying sap with it up that line labeled in red.

[TapTapTap]

Don't forget that the Hg will drop about 1" per each 13"of sap that is drawn up the tubes. Or about 1 inch of vacuum drop per 1 foot of sap lift. So if you're pulling a 8 ft sap column then it will drop about 8" of vacuum at the bottom side.

And, if you have a serious leak the the most obvious place to see are those lines that are pulling the sap. The air would be boiling through them in an obvious way.

Ken

[johnallin]

Seems as though a walk out that green line is the thing to do. The air (from the leak) is following the path of least resistance back to the releaser and is carrying sap with it up that line labeled in red.

Plan is to check the "Y" and "T" fittings, manifold and lifter with the leak detector first.
There are multiple possibilities right there, hopefully that's where my problem is.

Don't forget that the Hg will drop about 1" per each 13"of sap that is drawn up the tubes. Or about 1 inch of vacuum drop per 1 foot of sap lift. So if you're pulling a 8 ft sap column then it will drop about 8" of vacuum at the bottom side.
And, if you have a serious leak the the most obvious place to see are those lines that are pulling the sap. The air would be boiling through them in an obvious way. Ken

I think your right and plan to check there first. Will let you know how the leak detector performs..

Hey - thanks again to both of you. John

[TapTapTap]

Plan is to check the "Y" and "T" fittings, manifold and lifter with the leak detector first.
There are multiple possibilities right there, hopefully that's where my problem is.



I think your right and plan to check there first. Will let you know how the leak detector performs..

Hey - thanks again to both of you. John

Thanks for providing an interesting problem to think about.

If all else fails to reveal a solution, then I recommend installing a series of isolation valves around the perimeter of your setup. This would allow you to better diagnose the problem, drain back the flooded lines, and make it so that you can do a startup from zero vacuum without shutting down your entire woods. It would also make it easier to do a quick cleaning or maintenance during the season.

I'm still inclined to think that it's not about a vacuum leak. As I indicated previously, the action in the lines filled with sap would make it obvious if there was a substantial leak upstream. When my sap ladders first come on-line they will shake, bounce, and swoosh from air moving through.

Ken

[johnallin]

Well the leak detector works!
Ended being the stainless Y and T fittings.
Thing went off like Jimmy Hendrix playing Purple Haze…
I’m buying this tool. Pics attached.
First pic shows the T with detector flashing red.
Second picture shows dry line with frost from the leak
Thanks again for the replies and Fred for letting me trial it… making up for all the bad Clear Press comments I think.

[fred]

making up for all the bad Clear Press comments I think.
Attachment 22964 Attachment 22965

Well my feelings are still healing, it may be a long process.

[johnallin]

Well my feelings are still healing, it may be a long process.

... just remember..."dont take life too serious, nobody gets out alive anyways" <grin>